Question

Ex. 4. While covering a distance of 24 km, a man noticed that after walking for
1 hour and 40 minutes, the distance covered by him was
5/7 of the remaining distance.
What was his speed in metres per second ?
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Answer 1

Answer:

D=24km=24000 meters

d=5/7(D-d)

d=5/7(24000-d)

d=10000

1 hour 40 minutes =100 minutes = 6000 seconds

6000 seconds *X meters/second =10000 meters

X=10000/6000=5/3=1 2/3rds

His speed was 1 and 2/3rds meters per second, approximately 1.666… m/s

Answer 2

Answer:

Lets take the things given first

Total distance = 24km

D covered=\dfrac{5} {7} of D left

Time walked = 1hr 40 min = 53 hr

Lets take the speed as ‘ x ’kmph

Distance covered= speed X time

Distance= x X 53 hr

Distance= 5x3 km

remaining=total- covered

=(24- 5x3 )

We know that

distance covered= 57 distance left

5x3=57(24−5x3)

5x3=57 X 72−5x3

Further equating

7x=72−5x

12x=72

x =6 kmph

x =6 x 518 m/s

x = 53 m/s

x= 1.666….. m/s✍️✍️

2 method

D=24km=24000 meters

d=5/7(D-d)

d=5/7(24000-d)

d=10000

1 hour 40 minutes =100 minutes = 6000 seconds

6000 seconds *X meters/second =10000 meters

X=10000/6000=5/3=1 2/3rds

His speed was 1 and 2/3rds meters per second, approximately 1.666… m/s